Information technology (IT) influences our lives at many levels.
We use it to collect, process, communicate and present
information. IT controls high-tech processes as well as medical
diagnostic instruments and everyday home appliances. Computers
are linked in a global network and only a few years from now,
they will number one billion. The performance of microelectronic
circuits seems to be increasing one hundred-fold every ten years
- at unchanged prices. IT is viewed as a prime mover in the
economic upswing our society has experienced over the past
decade.

This year's Nobel Prize in Physics rewards contributions to the
early developments of microelectronics and photonics, focusing on
the integrated circuit, or "chip," as well as semiconductor
heterostructures for lasers and high-speed transistors.

The transistor was invented around Christmas 1947 and the
discoverers of the transistor effect were awarded the 1956 Nobel
Prize in Physics. Ten years after that discovery, transistors had
replaced vacuum tubes on a large scale. Beaches were being
flooded by pop music, and one of the inventors is said to have
exclaimed: "If only I had never invented that transistor."

Discrete transistors were soldered on circuit boards together
with other components. But the emerging computers required ten
thousands of transistors on the same board, a time-consuming and
error-prone task.

As a newly hired engineer, Jack Kilby did not get his two weeks
of vacation in the summer of 1958. Instead he had the privilege
of thinking undisturbed on working time. He designed a circuit
out of components made from a single semiconductor material that
had been processed in different ways. This had already been
suggested, but it was in conflict with the prevailing industrial
practice of producing parts in the cheapest available material.
On September 12, he was able to demonstrate that an integrated
circuit worked - the birth date of the integrated circuit is one
of the most important birth dates in the history of technology.
Since then, things have moved fast. Chips being made today
contain nearly a billion bits of memories or logic gates in
processors - the brains of computers.

What was needed was not only more, smaller and cheaper
transistors, but also faster ones. Early transistors were
relatively slow. Semiconductor heterojunctions were proposed as a
way of increasing amplification and achieving higher frequencies
and power. Such a heterostructure consists of two semiconductors
whose atomic structures fit one another well, but which have
different electronic properties. A carefully worked out proposal
was published in 1957 by Herbert Kroemer. Today, high-speed
transistors are found in mobile (cellular) phones and in their
base stations, in satellite dishes and links. There they are part
of devices that amplify weak signals from outer space or from a
faraway mobile telephone without drowning in the noise of the
receiver itself.

Semiconductor heterostructures have been at least equally
important to the development of photonics - lasers, light
emitting diodes, modulators and solar panels, to mention a few
examples. The semiconductor laser is based upon the recombination
of electrons and holes, emitting particles of light, photons. If
the density of these photons becomes sufficiently high, they may
begin to move in rhythm with each other and form a phase-coherent
state, that is, laser light. The first semiconductor lasers had
low efficiency and could only shine in short pulses.

Herbert Kroemer and Zhores Alferov suggested in 1963 that the
concentration of electrons, holes and photons would become much
higher if they were confined to a thin semiconductor layer
between two others - a double heterojunction. Despite a lack of
the most advanced equipment, Alferov and his co-workers in
Leningrad (now St. Petersburg) managed to produce a laser that
effectively operated continuously and that did not require
troublesome cooling. This was in May 1970, a few weeks earlier
than their American competitors.

Lasers and light emitting diodes (LEDs) have been further
developed in many stages. Without the heterostructure laser,
today we would not have had optical broadband links, CD players,
laser printers, bar code readers, laser pointers and numerous
scientific instruments. LEDs are used in displays of all kind,
including traffic signals. Perhaps they will entirely replace
light bulbs. In recent years, it has been possible to make LEDs
and lasers that cover the full visible wavelength range,
including blue light.

I have emphasized the technical consequences of these
discoveries, since these are easier to explain than the
spectacular scientific breakthroughs that they have also led to.
Challenging problems and matching resources have led to
large-scale basic research. The advanced materials and tools of
microelectronics are being used for studies in nanoscience and of
quantum effects. Scientific experiments and computations are, of
course, highly computerized.

Semiconductor heterostructures can be regarded as laboratories of
two-dimensional electron gases. The 1985 and 1998 Nobel Prizes in
physics for quantum Hall effects were based on such confined
geometries. They can be reduced further to form one-dimensional
quantum channels and zero-dimensional quantum dots for future
studies.

Drs. Alferov, Kilby and Kroemer,

I have briefly described some
consequences of your discoveries and inventions. Few have had
such a beneficial impact on mankind as yours. I also predict that
there will be continued development, as we may be only halfway
through the information technology revolution. New effects may
appear as a result of basic research. When, what and where we
cannot say, but we can be sure they will come.

On behalf of the Royal Swedish Academy of Sciences, I would like
to convey the warmest congratulations to you and ask you to step
forward to receive the Nobel Prize from the hands of His Majesty
the King.